@Matt_Byrne, Yet Another Related Posts Plugin is able to pull up posts based on common tags as well as other criteria, but it currently can only show an excerpt aside from the post title. The ability to show other metadata, such as post date or custom fields, is coming in the next revision, due out in about a month.

@Matt_Byrne - if you just want to display posts from a certain category, you should just write a custom query_post... be warned, though, it's a little tricky to get everything working if it's on the same page as another Loop.